The invention relates generally to gas turbines and more specifically to air-staged diffusion nozzles for gas turbine combustors.
In a diffusion nozzle for a gas turbine combustor, the fuel begins mixing with air in swirl vanes and then flows and expands in a swirling motion within the burner tube space of the combustor for mixing. In the current diffusion nozzles, a low velocity region was observed in the burner tube at the center of diffusion nozzle. High carbon formation on the diffusion nozzle tip has been identified during the start up as well as part load operation. For a highly reactive fuel, higher temperature is observed on the nozzle tip due to proximity of the flame. Further, enhanced mixing of the gas-fuel and air in the burner tube can result in reduced emissions from the gas turbine.
Accordingly, there is a need for a diffusion nozzle with a gas-fuel that provides for cooling of the nozzle tip while at the same time improving mixing of the fuel and air.